Dynamics of predator-prey systems are strongly affected by the strategic behavior of both predator and prey. Thus, understanding the relationship between the strategic behavior and the species survival is necessary to comprehend the system resilience and stability. In the present study, we constructed a spatially explicit lattice model to simulate integrative predator (wolf)-prey (two rabbit species)-plant relationships. Wolves have only the hunting strategy, while rabbits have the hunting-escaping strategy. When a rabbit simultaneously encounters its predator (wolves) and prey (plant), either hunting or escaping should take priority. Hunting priority is referred to as hunting preferred strategy (HPS), while escape priority is referred to as escape preferred strategy (EPS). These strategies are associated with some degree of willingness to either hunt (H) or escape (E). One rabbit species takes HPS (HPS-rabbit) and the other rabbit species takes EPS (EPS-rabbit). We investigated the changes in predicted population density for wolves, rabbits, and plant with changes in the value of H and E. Simulation results indicated that EPS-rabbit had a greater chance for survival than HPS-rabbit regardless of the initial density of EPS-rabbit, and the chance was optimized at the appropriate values of E and H. In addition, we briefly discussed the development of our model as a tool for understanding behavioral strategies in specific predatorprey interactions.

Understanding the predator-prey dynamics is essential to comprehend the ecosystem resilience and stability because ecosystems consist of dynamically interacting subsystems with predator-prey relationship. The relationship is likely to be of the predator and prey hunting-escaping strategy. Thus, to better understand the ecosystems, we should comprehend how the hunting and the escaping strategy affect the ecosystems. To do so, we constructed a spatially explicit lattice model to simulate the integrative predator-prey-plant relationships. When an individual simultaneously encounters its predator and/or prey, the individual should take priority between the two strategies. When the hunting (or escaping) strategy takes priority, we call it hunting preferred strategy, HPS, (or escaping preferred strategy, EPS). Each strategy was characterized by the willingness for each strategy. The degree of willingness was represented as H (for hunting) and E (for escaping). Higher value of H (or E) means stronger willingness for hunting (or escaping). We investigated the population density of each species for different values of H and E for HPS and EPS. The main conclusion that emerges from this study was that HPS plays a positive role in the ecosystem stability. In addition, we briefly discussed the development of the present model to be used to understand the predator-prey interaction in specific species.

Four-week repeated-dose toxicity of Misaengtang (MST) was evaluated according to Toxicity Test Guideline of Korea Food and Drug Administration using 6-week-old Sprague-Dawley rats. Based on the results of preliminary single-dose toxicity study, confirming safety up to an upper-limit dose, MST was dissolved in drinking water and orally administered at doses of 500, 1,000, or 2,000 mg/kg for 28 days. All doses including the upper-limit limited dose (2,000 mg/kg) of MST did not cause any abnormalities of rats, including mortality, clinical signs, body weight gain, feed/water consumption, necropsy findings, organ weights, hematology and blood biochemistry. Rather, high doses (1,000-2,000 mg/kg) of MST reduced the serum levels of alanine transaminase, aspartate transaminase, creatinine phosphokinase, lactate dehydrogenase and triglycerides, in addition to an increase in glucose, indicative of protective effects on hepatic and muscular injuries. Both maximum-tolerable dose and no-observed-adverse-effect level were not determined. The results indicate that long-term intake of high-dose MST might not induce general adverse-effects.

The Earth’s outer radiation belt often suffers from drastic changes in the electron fluxes. Since the electrons can be a potential threat to satellites, efforts have long been made to model and predict electron flux variations. In this paper, we describe a prediction model for the outer belt electrons that we have recently developed at Chungbuk National University. The model is based on a one-dimensional radial diffusion equation with observationally determined specifications of a few major ingredients in the following way. First, the boundary condition of the outer edge of the outer belt is specified by empirical functions that we determine using the THEMIS satellite observations of energetic electrons near the boundary. Second, the plasmapause locations are specified by empirical functions that we determine using the electron density data of THEMIS. Third, the model incorporates the local acceleration effect by chorus waves into the one-dimensional radial diffusion equation. We determine this chorus acceleration effect by first obtaining an empirical formula of chorus intensity as a function of drift shell parameter L*, incorporating it as a source term in the one-dimensional diffusion equation, and lastly calibrating the term to best agree with observations of a certain interval. We present a comparison of the model run results with and without the chorus acceleration effect, demonstrating that the chorus effect has been incorporated into the model to a reasonable degree.

Whistler mode chorus wave is considered to play a critical role in accelerating and precipitating the electrons in the outer radiation belt. In this paper we test a conventional scenario of triggering chorus using THEMIS satellite observations of waves and particles. Specifically, we test if the chorus onset is consistent with development of anisotropy in the electron phase space density (PSD). After analyzing electron PSD for 73 chorus events, we find that, for ~80 % of them, their onsets are indeed associated with development of the positive anisotropy in PSD where the pitch angle distribution of electron velocity peaks at 90 degrees. This PSD anisotropy is prominent mainly at the electron energy range of ≤ ~20 keV. Interestingly, we further find that there is sometimes a time delay among energies in the increases of the anisotropy: A development of the positive anisotropy occurs earlier by several minutes for lower energy than for an adjacent higher energy.